By translating inequalities into equations (e.g., x greater than 0 can be written x- absolute value of x = 0) and forming equations for unions and intersections of solution sets, students can develop equations for polygons. The method can be generalized to yield equations in three dimensions. (SD)

Using play money, students buy and sell six types of stock certificates at prices determined periodically by tossing three dice; all students participate as investors, brokers, or banker. In addition to gaining practice on computational skills in a motivational game, students study the real stock market concurrently. (SD)

Beginning with a construction problem admitting a classical solution, the authors provide other solutions based on algorithmic estimation and transformational geometry. The latter methods are generalized to suggest solutions to other problems; hints to these solutions are provided. Teacher-student discussion could lead in many directions. (SD)

Proliferation of mathematical knowledge prohibits individual reduplication of all results and causes mathematicians to accept much on faith. To convey the spirit of the mathematical community, and provide maximum content coverage, instruction should allow students to accept some theorems without proof. Students would then find mathematics less…

After describing desirable characteristics of a student's first encounter with proof, and listing skills prerequisite for the proposed lesson (knowledge of some operational systems), the author describes in detail an introductory session in which students prove consequences of commutativity and associativity for a system supposedly encountered on…

Students, playing the game described, develop strategies for guessing the four-digit number chosen by the opponent. The rules of the game are easily understood by low achievers, yet strategy development is challenging to advanced students. The game can be extended to numbers having more digits. (SD)

Strategies are developed for establishing impossibility proofs for construction of a given shape from pieces of a set of soma cubes. The activities illustrated were developed with sixth graders; students, with guidance, established the proofs. Additional activities and problems are suggested. (JP)

The social science finding that two-thirds of a population of successful males are first-born sons provided the motivation for a problem solved by a 12th grade honors class. The class proved that the probability of choosing a first-born son from a male population is about two-thirds. (JP)

Tac Tix is a board game for two players having a mathematical optimum strategy for play. The strategy can be discovered by application of general problem solving techniques. (JP)